The present invention relates generally to material transport vehicles and trailers, and more particularly to material transport vehicles and trailers that have a xe2x80x9clive bottomxe2x80x9d or endless conveyor for discharging material to the rear of the vehicle or trailer.
Live bottom trailers and trucks are frequently used to transport a variety of loose materials such as sand, gravel, hot mix asphalt, recycled materials, salt, low slump concrete, and the like. One primary advantage of using a live bottom trailer or live bottom truck as opposed to a conventional hydraulic hoist dump truck is that a live bottom does not need to be hoisted or vertically elevated to discharge material from the rear of the truck bed. As such, live bottoms do not have the risks associated with conventional hydraulic hoist dump trucks such as interference with low electrical or telephone wires and the potential for tipping over due to vertical elevation of a hoisted dump body. Live bottoms also have certain operational advantages when feeding material into other hoppers. For example, live bottoms are easier to use when filling a hopper of an asphalt paver with hot mix asphalt material.
While live bottoms have their advantages, they are not without drawbacks. For example, one significant problem is that federal regulations require commercial vehicles to either have rear under-ride guards to prevent a smaller vehicle or car from riding underneath the trailer in the event of a rear end collision, or alternatively to have a rear tire location within 12 inches of the rear end of the trailer. For example such regulations are promulgated by the Department of Transportation, National Highway Traffic Safety Administration under CFR part 571, FMVSS 223 and 224, such regulations are hereby incorporated by reference.
Although the solution of simply locating the rear tires closer to the rear end would seem to at first blush be an easy way of solving the problem, such a solution would have the significant drawback of rendering live bottoms less practical. In particular, when it is necessary to feed material from the live bottom into another hopper such as an asphalt paver, the problem would arise that the rear end of the trailer would only stick a maximum of about 12 inches into the asphalt paver rather than more deeply toward the center or rear of the asphalt paver. As such, material would be directed less deep into the hopper of the asphalt paver and be subject to spillage out the sides of the asphalt paver and otherwise cause it to be used at less than its full capacity. Because of these drawbacks, this possible solution has not been implemented in the relevant art prior to the solution of the present invention.
The other solution of implementing a rear under-ride guard is also not desirable in that it would also interfere with the body of the asphalt paver. The additional costs of providing a rear under-ride and maintaining a rear under-ride guard over the life of the trailer is also undesirable. Rear under-ride guards also contribute weight to the vehicle and can further limit the amount of material carried by the trailer due to highway road weight limits.
The Inventor of the present invention has also realized that there have been other long-felt deficiencies in the more general material transport art as well. For example, material transport vehicles both of the live bottom type as well as the conventional hydraulic hoist type both are typically deficient from a practical standpoint in being able to adequately control the material discharge from the rear the vehicle and direct the material into more specific desirable locations.
It is a primary objective of the present invention to provide more practical live bottom material transport apparatus.
In that regard, it is another primary objective of the present invention to provide a live bottom material transport apparatus that is capable of delivering asphalt material deeper into asphalt pavers or otherwise direct material further rearwardly from the rear end of the live bottom hopper.
It is an objective of the present invention to provide a live bottom material transport apparatus that meets federal regulations with respect to rear under-ride guard requirements while at the same time being capable of discharging material a satisfactory or even improved distance relative to prior art live bottoms.
It is still another objective to provide a live bottom material transport apparatus that obtains better control over placement of material discharged from the rear of the live bottom hopper.
In accordance with these and other objectives, the present invention is directed towards a mobile live bottom transport apparatus that includes a pair of horizontally outwardly pivoting doors or other rearward projecting sidewall extensions at the rear end of the hopper. The doors effectively extend the rear end of the live bottom trailer by projecting horizontally rearwardly when the doors are open. It is an advantage of the outwardly pivoting doors that material is directed further rearwardly from the live bottom and that material is prevented from spilling out along the sides. The invention may be incorporated into the truck bed that is permanently attached to a vehicle, or alternatively incorporated into a trailer that may be selectively attached and detached from a vehicle.
It is an aspect of the present invention that the rear wheels of the vehicles can be practicably located further rearward close enough to the rear end of the trailer such that a rear under-ride guard is not necessary by virtue of the doors.
It is another aspect of the present invention that the doors are actuated to open and close the doors. The doors may be selectively actuated to provide a larger opening or a smaller opening in the discharge area of the trailer. Preferably a distributed control is provided such that the doors can be actuated independently of each other such that material can be directed left or right as desired. It is a further aspect that a lock in the preferred form of an over center condition in the mechanical linkage is provided to automatically lock the doors when in the closed position such that if pressure is lost in the actuators, the doors remain closed despite the fact that the load carried in the hopper is urging the doors open.
Other objectives and advantages of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.